/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use _in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions _in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer _in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


using System;
using System.IO;
using EffiProzDB.Lib;



namespace EffiProzDB.Persist
{

    /**
     * Mixe NIO / non-NIO version of ScaledRAFile.
     * This class is used only for storing a CACHED
     * TABLE .data file and cannot be used for TEXT TABLE source files.
     *
     * Due to various issues with java.nio classes, this class will use a mapped
     * channel of fixed size. After reaching this size, the file and channel are
     * closed and a new one opened, up to the maximum size.
     *
     * @author fredt@users
     * @version  1.8.0.5
     * @since 1.7.2
     */
    public class ScaledRAFileHybrid : ScaledRAInterface
    {

        public Database database;
        public string fileName;
        public bool _isReadOnly;
        public bool _wasNio;
        public long maxLength;
        public ScaledRAInterface store;

        public ScaledRAFileHybrid(Database database, string name,
                                  bool readOnly)
        {

            this.database = database;
            this.fileName = name;
            this._isReadOnly = readOnly;

            newStore(0);

            this._wasNio = store.wasNio();
        }

        public long length()
        {
            return store.length();
        }

        public void seek(long position)
        {
            checkSeek(position);
            store.seek(position);
        }

        public long getFilePointer()
        {
            return store.getFilePointer();
        }

        public int read()
        {

            checkLength(1);

            return store.read();
        }

        public void read(byte[] b, int offset, int length)
        {
            checkLength(length);
            store.read(b, offset, length);
        }

        public void write(byte[] b, int offset, int length)
        {
            checkLength(length);
            store.write(b, offset, length);
        }

        public int readInt()
        {

            checkLength(4);

            return store.readInt();
        }

        public void writeInt(int i)
        {
            checkLength(4);
            store.writeInt(i);
        }

        public long readLong()
        {

            checkLength(8);

            return store.readLong();
        }

        public void writeLong(long i)
        {
            checkLength(8);
            store.writeLong(i);
        }

        public void close()
        {
            store.close();
        }

        public bool isReadOnly()
        {
            return store.isReadOnly();
        }

        public bool wasNio()
        {
            return _wasNio;
        }

        public bool canAccess(int length)
        {
            return true;
        }

        public bool canSeek(long position)
        {
            return true;
        }

        public Database getDatabase()
        {
            return null;
        }

        private void checkLength(int length)
        {

            if (store.canAccess(length))
            {
                return;
            }

            newStore(store.getFilePointer() + length);
        }

        private void checkSeek(long position)
        {

            if (store.canSeek(position))
            {
                return;
            }

            newStore(position);
        }

        void newStore(long requiredPosition)
        {

            long currentPosition = 0;

            if (store != null)
            {
                currentPosition = store.getFilePointer();

                store.close();
            }

            if (requiredPosition <= ScaledRAFile.MAX_NIO_LENGTH)
            {
                try
                {
                    store = new ScaledRAFileNIO(database, fileName, _isReadOnly,
                                                (int)requiredPosition);

                    store.seek(currentPosition);

                    return;
                }
                catch (Exception) { }
            }

            store = new ScaledRAFile(database, fileName, _isReadOnly);

            store.seek(currentPosition);
        }
    }
}
